Hello Rene, Yes, but a TNtuple will get too big, if a lot of data points are collected. With a histogram, the binning reduces memory usage. So TNtuple would be more powerful in principle, but is unpractical when dealing with large amounts of data. So a question would be: are there plans to implement this projection feature of 3D histograms? Thanks, Mike Lisa +-------------------------------------------------------------------+ | Mike Lisa | email: lisa@mps.ohio-state.edu | | Department of Physics | | | 2156 Smith Laboratory | Van de Graaff <--- usually here | | Ohio State University | ph: (614) 292-4775 / fax: 292-4833 | | 174 West 18th Avenue | | | Columbus, OH 43210 | http://vdgus1.mps.ohio-state.edu/~lisa/ | +-------------------------------------------------------------------+ On Thu, 29 Jul 1999, Rene Brun wrote: > Hi Valeri, > Your request could be implemented. To be complete, one has to consider > all possible combinations, including 1-d projections. > > I did not put much effort in this area, as I believe that is is more > general > and powerful to define a small TNtuple object with x,y,z from which you > can > already make all kinds of projections 1-d, 2-d and 3-d including > selections. > > Rene Brun > > > Valeri Fine (Faine) wrote: > > > > ----- Original Message ----- > > From: Selemon Bekele <bekele@pacific.mps.ohio-state.edu> > > To: STAR software <starsofi-l@bnl.gov> > > Sent: 29 èþëÿ 1999 ã. 10:38 > > Subject: projecting a histogram > > > > > > > > > > > I have a three dimensional histogram which I want to project to a certain > > > axis. Is there a way how to do it in root4star? I cheked the root class > > > library and found in a class which relates to one dimensional histograms a > > > method which projects only to the third axis which it calls Z. It would be > > > nice if two more methods could be added so that one can project also onto > > > the other two axes separately. For the time being, a way around this problem > > > is to fill three histograms where each component is passed as a third > > > argument: > > > > > > Fill(x,y,z),Fill(z,x,y),Fill(y,z,x) > > > > > > and do the projection. > > > ******************************************* > > > > > > Selemon Bekele > > > e-mail bekele@pacific.mps.ohio-state.edu > > > Tel. (614)294-4863 (home) > > > > > > ******************************************* > > > > > > > > > > > > >
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